Leakage Of Medium Research Articles

Leakage Control Mechanisms and Strategies for Hydraulically Driven Controllable Rod Seals

Abstract The primary function of rod seals in hydraulic systems is to prevent the leakage of the hydraulic medium, which would otherwise result in environmental pollution and the loss of energy. However, the leakage control performance of conventional rod seals is limited by the level of product design. As a result, the performance of these seals will gradually degrade during the service process. Furthermore, it is not possible to adaptively adjust the performance of these seals in response to changes in operating conditions. Hydraulically controllable rod seals (HCRS) can be driven hydraulically to adjust the internal stress distribution of the seal to regulate the sealing performance. This may be an effective solution, although the leakage control mechanism and strategy remain unclear. This paper employs a thermoelastohydrodynamic mixed lubrication model to comparatively analyze the behaviors and performances of the HCRS with or without a cavity structure. The leakage control mechanism of the HCRS is revealed, namely that it is achieved by increasing the interface contact pressure and reducing the fluid film thickness through external pressurization. Furthermore, the functional relationship between the sealing performance and the regulating variables under different operating conditions is obtained through multivariate regression analysis, thereby forming the quantitative leakage control strategy of the HCRS.

Leakage Characteristics and Experimental Research of Staggered Labyrinth Sealing

The staggered labyrinth seal is widely used in aerospace, transportation, mining, and other fields due to its advantages of adapting to high speed, reliable sealing performance, and low or even frictionless friction between dynamic and static rotors. The traditional calculation method of labyrinth seal leakage mostly focuses on the fact that the internal medium is an ideal gas and only considers a single effect, which cannot accurately describe the leakage of liquid medium lubricating oil in the labyrinth seal. Therefore, this study focuses on the leakage characteristics of labyrinth seals, and it proposes a leakage calculation method based on liquid medium in view of the shortcomings of existing calculation methods under liquid medium conditions. By considering the thermodynamic and frictional effects of the staggered labyrinth sealing, the resistance loss and thermodynamic effect of the lubricating oil in the sealing cavity were analyzed. The flow field analysis was used to reveal the leakage law of lubricating oil under different conditions, and the factors such as total inlet pressure, spindle speed, and sealing clearance were considered. Finally, the leakage characteristics of the staggered labyrinth seal and the accuracy of the calculation method of the leakage of the staggered labyrinth seal under multiple effects were revealed through experimental verification. This study provides useful guidance for the performance optimization of labyrinth seals in practical applications.

Research progress of thermoregulating textiles based on spinning of organic phase change fiber of energy storage

Thermal energy storage can contribute to the reduction of carbon emissions, motivating the applications in aerospace, construction, textiles and so on. Phase change materials have been investigated extensively in the field of high-performance intelligent thermoregulating fabrics for energy storage. Advances toward fibers or fabrics for thermo regulation are developed, but leakage of phase change medium is a concern when directly coated or filled with fibers or fabrics. Thus, different spinning methods have appeared to integrate phase change materials into copolymer fiber to prepare phase change fiber. The present review has been divided into three parts and first deals with spinning technologies such as wet spinning, melt spinning, electrostatic spinning, and centrifugal spinning with the thermal properties and mechanical properties of phase change fiber. Among them, the phase change medium loading in the phase change fiber with wet spinning is up to 70 wt.%, while the fiber strength is below 2.12 cN/dtex. In contrast, phase change fiber prepared by melt spinning achieves a breaking strength of up to 37.31 cN/dtex, but with an enthalpy of only 8.48 kJ/kg. Considering electrostatic spinning, not only enthalpies are satisfactory but the fiber diameters are mostly below 1000 nm, matching with the softness requirement for fabric. Moreover, centrifugal spinning enables efficient production of phase change fiber of large enthalpy by controlling spinning parameters such as rotational speed and spinning fluid concentration. The second part reports that the thermal management effects of different intelligent thermo regulating fabrics are evaluated by designed experiments or simulations to investigate further the more comfortable conditions of thermal comfort of humans. Simulation and experimental results show that the energy storage of smart fabrics extends the time duration of thermal comfort by more than 300 s. In the last part, multifunctional intelligent thermoregulating fabrics are systematically discussed, such as light and heat response, ultraviolet resistance, air permeability, and water resistance. Practical applications of phase change fibers and intelligent thermoregulating fabrics should be further studied and broadened in the future.

Prospective clinical trial of EUS–guided choledochoduodenostomy without fistula dilation for malignant distal biliary obstruction

ABSTRACT Background and Objectives During EUS–guided choledochoduodenostomy (EUS-CDS), fistula dilation before stent insertion is associated with adverse events (AEs), such as bile leakage and peritonitis. We hypothesized that EUS-CDS without fistula dilation using a novel self-expandable metal stent (SEMS) with a thin delivery system could overcome this problem, and we conducted this study to evaluate its feasibility and safety. Methods This was an open-label, single-arm, phase II study at a single institution. We planned EUS-CDS without fistula dilation using a fully covered SEMS with a 5.9-Fr delivery system for unresectable malignant distal biliary obstruction. The primary outcome was overall technical success. Secondary outcomes were technical success without fistula dilation, procedure time, functional success, time to recurrent biliary obstruction, and AEs. The planned sample size was 25 patients. Results In total, 24 patients were included in this study. In 21 patients, EUS-CDS was performed as primary drainage. The overall technical success rate was 100% (24 of 24 patients). The technical success rate without fistula dilation was 96% (23 of 24). The median procedure time was 16 min (range, 10–66 min). The functional success rate was 96% (23 of 24). The median time to recurrent biliary obstruction was 148 days (95% confidence interval, 29–266 days). There were no procedure-related AEs. Furthermore, computed tomography immediately after the procedure showed no leakage of contrast medium into the abdominal cavity in any patient. Conclusions EUS–guided choledochoduodenostomy without fistula dilation using a fully covered SEMS with a 5.9-Fr delivery system is feasible with a high probability and can be achieved quickly while effectively preventing bile leakage and peritonitis.

Research on PID Controller of Excavator Electro-Hydraulic System Based on Improved Differential Evolution

An electrical hydraulic control system (electro-hydraulic system) is thought to be a key component in excavator operation systems. Control methods with fixed parameters may not yield optimal system performances because a hydraulic system has various nonlinear uncertainties due to the leakage and compressibility of the fluid medium. Hence, a novel PID controller based on improved differential evolution (IDE) is introduced to excavator electro-hydraulic systems for interconnected hydraulic systems. The proposed algorithm not only adjusts the PID parameters of the different working conditions but also adjusts the scaling factor and crossover probability. Then, the proposed PID controller based on IDE and the excavator bucket control system are modeled and simulated on the MATLAB simulation platform. The simulation results demonstrate that the proposed controller has better performance in settling time, rise time, and convergence speed compared to the PID controller based on standard differential evolution and the Ziegler–Nichols (ZN) PID controller with a novel object function. Eventually, the IDE-PID controller is assessed on a 23-ton excavator, and good transient behavior and trajectory accuracy are obtained in comparison to the SDE-PID controller.

Partial hepatectomy for a patient with Rendu–Osler–Weber disease: a case report

BackgroundRendu–Osler–Weber disease (Osler disease) is a genetic disease with an autosomal dominant inheritance pattern. It is characterized by widespread telangiectasia in multiple organs. Liver involvement of FNH is relatively common, but liver cancer is very rare, and there are few reports on hepatectomy or postoperative complications. We report a very rare case in which hepatectomy was performed for a patient with Osler disease.Case presentationThe patient was a 39-year-old man with Osler disease who had been previously diagnosed with multiple FNH and who had been followed for 8 years. During follow-up, the diameter of an S6 lesion gradually increased from 30 to 50 mm; no other lesions increased in size. We decided to perform partial liver resection as total biopsy for the growing tumor, due to the possibility that the growing tumor lesion included malignant components. The pathological examination revealed no obvious malignancy, which was finally diagnosed FNH. The postoperative course was uneventful and he was discharged on the 14th day after surgery. In the second month after discharge, he was transferred to our hospital with sudden abdominal pain in the right hypochondrium with severe tenderness. CT showed extravasation of contrast medium from the hepatic dissection surface in S6, and the hematoma extended to the pelvic floor. Emergency IVR was performed and revealed leakage of the contrast medium from the A6 branch. We embolized the A6 with Lipiodol. After embolization, there were no major problems, and the patient was discharged on the 9th day after the treatment.ConclusionsPostoperative hemorrhage often occurs within 24 h after surgery, and 2 months after surgery is considered to be the late stage of the wound healing process, and postoperative hemorrhage at this timepoint is considered rare. This unexpected delayed postoperative hemorrhage may have been related to the etiology and pathology of Osler disease, nevertheless, case reports of hepatectomy for patients with Osler disease are limited. We, therefore, report the present case with a review of the relevant literature.

Peripheral Retinal Leakage after Intravenous Administration of a Gadolinium-based Contrast Agent: Age Dependence, Temporal and Inferior Predominance and Potential Implications for Eye Homeostasis.

Peripheral retinal leakage (PRL) of contrast medium from the ora serrata (i.e., the peripheral part of the retina) was recently reported in normal eyes using ultra-widefield fluorescein angiography. We occasionally see PRL of gadolinium-based contrast agents (GBCAs) in the vitreous from the temporal and inferior sides of the ora serrata on MR images of subjects without ophthalmic disease. In this study, we retrospectively evaluated these MR images to determine if PRL was associated with aging. We also evaluated whether the initial leakage appeared in the temporal and inferior sides, and whether there was uniform distribution within the vitreous after 24 hours. In 127 subjects (9 volunteers, 85 patients with sudden deafness, and 33 patients with a suspicion of endolymphatic hydrops), pre- and post-contrast-enhanced heavily T2-weighted 3D-fluid attenuated inversion recovery (FLAIR) images were obtained. The presence or absence of PRL was subjectively evaluated. For patients with a suspicion of endolymphatic hydrops, 3D-real inversion recovery (IR) images were also obtained at pre-, 10 mins, 4 hours, and 24 hours after intravenous administration (IV) of GBCA. Four circular ROIs were placed in the vitreous humor and the signal intensity was measured. In the cases with PRL (n = 88) and without PRL (n = 47), the median age was 59 and 47 years, respectively (P = 0.001). At 4 hours after IV-GBCA, the mean signal increase in the inferior temporal ROI was greater than all the other ROIs. At 24 hours after IV-GBCA, no significant difference in signal intensity was observed for the four ROIs. PRL of GBCA is age-dependent and occurs mainly from the inferior temporal side of the ora serrata. The contrast effect was uniformly distributed at 24 hours after IV-GBCA. Future observations in a variety of diseases will determine the clinical significance of these findings.

Half-wet nanomechanical sensors for cellular dynamics investigations

Testing devices based on cell tracking are particularly interesting as diagnostic tools in medicine for antibiotics susceptibility testing and in vitro chemotherapeutic screening.In this framework, the application of nanomechanical sensors has attracted much attention, although some crucial aspects such as the effects of the viscous damping, when operating in physiological conditions environment, still need to be properly solved. To address this problem, we have designed and fabricated a nanomechanical force sensor that operates at the interface between liquid and air.Our sensor consists of a silicon chip including a 500 μm wide Si3N4 suspended membrane where three rectangular silicon nitride cantilevers are defined by a lithographically etched gap. The cantilevers can be operated in air, fully immersed in a liquid environment and in half wetting condition, with one side in contact with the solution and the opposite one in air. The formation of a water meniscus in the gap prevents the leakage of medium to the opposite side, which remained dry and is used to reflect a laser to measure the cantilever deflection. This configuration enables to keep the cells in physiological environment while operating the sensor in dry conditions.The performance of the sensor has been applied to monitor the motion and measures the forces developed by migrating breast cancer cell. The functionalization of one side of the cantilever and the use of a purposely designed chamber of measurements enable the confinement of the cell only on one side of the cantilever.Our data demonstrate that this approach can distinguish the adhesion and contraction forces developed by different cell lines and may represents valuable tool for a fast and quantitative in-vitro screening of new chemotherapeutic drugs targeting cancer cell adhesion and motility.

Closure of a dural defect as a cause of superficial siderosis: does early dural repair lead to a better outcome? Illustrative case.

Superficial hemosiderosis (SS) of the central nervous system is a rare condition that is caused by chronic, repeated hemorrhage into the subarachnoid space. The subsequent deposition of hemosiderin in the brain and spinal cord causes neurological deterioration. In this report, the authors describe a repair procedure for SS associated with a dural defect in the thoracic spine. A 75-year-old man presented with tinnitus symptoms that began about 1 year prior. Subsequently, his hearing loss progressed, and he gradually became unsteady on walking. Magnetic resonance imaging (MRI) of the head showed diffuse hemosiderin deposition on the surface of the cerebellum. Thoracic MRI showed ventral cerebrospinal fluid leakage of T2-7, and computed tomography myelography showed leakage of contrast medium that appeared to be a dural defect. Dural closure was successful, and MRI showed decreased fluid collection ventral to the dura. The patient's symptoms of wobbliness on walking and tinnitus improved dramatically from the postoperative period. Dural abnormalities of the spine must always be considered as one of the causes of SS. Early dural closure is an effective means of preventing the progression of symptoms.

Imaging features of marginal ulcers on multidetector CT

To assess the inter-reader agreement and frequency of various imaging findings of marginal ulcers on computed tomography (CT) in a series of patients with endoscopically or surgically confirmed marginal ulcer disease. This was a institutional review board-approved retrospective analysis involving a single academic institution. Eighty patients with a gastro-enteric anastomosis with confirmed marginal ulcer on endoscopy or surgery and multidetector (MD)CT performed within a month reviewed by two fellowship-trained abdominal radiologists to assess for the presence or absence of predetermined imaging characteristics categorised under signs of inflammation, signs of penetration, signs of perforation, and signs of obstruction. Inter-rater reliability was assessed using the Cohen kappa test. Findings of perforation had moderate to substantial agreement, including the presence of extraluminal air, extraluminal fluid, and leakage of oral contrast medium (kappa 0.83 [0.61, 1.05], 0.57 [0.35, 0.79] and 0.75 [0.18, 1.31], respectively) although these were present relatively infrequently (23-26%, 30-43%, 3-4%, respectively). Additional imaging characteristics with moderate agreement were the presence of perienteric fat stranding, a dilated stomach proximal to the anastomosis, and penetration into adjacent organ (kappa 0.45 [0.23, 0.69], 0.47 [0.26, 0.69], and 0.47 [0.25, 0.69], respectively) which were variably present (80-88%, 11-16%, 5%, respectively). Wall thickening and contour abnormalities, although frequently present (61-90% and 60-80%, respectively) had only slight to fair agreement (kappa 0.09 [-0.14, 0.30] and 0.29 [0.07, 0.51]). Signs of perforation have high inter-reader agreement but occur relatively infrequently. Fat stranding, wall thickening, and contour abnormalities are much more common; however, only fat stranding had moderate agreement.

Development of an enterocutaneous fistula from an intestinal perforation in a patient with autosomal dominant polycystic kidney disease

We herein report a case of enterocutaneous fistula in a patient with autosomal dominant polycystic kidney disease (ADPKD). A 37-year-old Japanese man was admitted to our hospital. Three months prior to transfer to our hospital, he developed intense flank pain with gross hematuria. His serum creatinine had decreased to 7.8 mg/dL and hemodialysis was started, but gross hematuria persisted and he developed hypotension. Upon admission, plain chest radiography did not reveal any free air, but computed tomography (CT) showed generalized ventral subcutaneous air from the head to the lower extremities and enlarged kidneys. Enterography showed leakage of contrast medium from the descending colon into the subcutaneous area. C-reactive protein was 23.1 mg/dL. A colostomy was placed in the transverse colon proximal to the perforation, and systemic subcutaneous drainage was performed. The fever subsequently resolved, and the C-reactive protein test became negative. Three months later, renal artery embolization was performed, and 12 months thereafter, CT showed a marked decrease in kidney size. We assume that a markedly enlarged kidney leaded to intestinal perforation, which developed into an enterocutaneous fistula. Consequently, intestinal fluid leaked into the subcutaneous cavity of the abdominal wall and spread systemically, resulting in extensive subcutaneous abscesses.

Bio-inspired optimization design and fluid–solid-thermal multi-field verification analysis of labyrinth seal

Labyrinth seals are widely used in turbomachinery devices to prevent the leakage of fluid medium in seal structures. Under high parametrical environments, the heat generated by frictional resistance of the turbulence between the stator and rotor walls not only increases the temperature of the fluid and the solid, but also reduces the operation efficiency of the device. Therefore, it is necessary to implement the fluid–solid-thermal multi-field analysis of labyrinth seals and propose a comprehensive optimization design of the load-bearing and heat insulation. In the present study, inspired by a bionic snail shell, a sandwich structure with load-bearing material on both upper and lower surfaces and the heat insulation material in the middle is obtained through the genetic algorithm optimization. Then, the luid-solid-thermal multi-field analysis of the labyrinth seal with the sandwich structure is carried out. It is verified that the layer arrangement and layer thickness ratio of the bionic structure ensured the optimal performance of load-bearing and heat insulation. After changing the layer arrangement or layer thickness ratio, the comprehensive performance of load-bearing and heat insulation is obviously weakened. The result shows that the bionic multilayer sandwich structure can be applied to the labyrinth seal to achieve optimal comprehensive performance of load-bearing and heat insulation.

Testing 3D printed biological platform for advancing simulated microgravity and space mechanobiology research

The advancement of microgravity simulators is helping many researchers better understanding the impact of the mechanically unloaded space environment on cellular function and disfunction. However, performing microgravity experiments on Earth, using simulators such as the Random Positioning Machine, introduces some unique practical challenges, including air bubble formation and leakage of growth medium from tissue culture flask and plates, all of which limit research progress. Here, we developed an easy-to-use hybrid biological platform designed with the precision of 3D printing technologies combined with PDMS microfluidic fabrication processes to facilitate reliable and reproducible microgravity cellular experiments. The system has been characterized for applications in the contest of brain cancer research by exposing glioblastoma and endothelial cells to 24 h of simulated microgravity condition to investigate the triggered mechanosensing pathways involved in cellular adaptation to the new environment. The platform demonstrated compatibility with different biological assays, i.e., proliferation, viability, morphology, protein expression and imaging of molecular structures, showing advantages over the conventional usage of culture flask. Our results indicated that both cell types are susceptible when the gravitational vector is disrupted, confirming the impact that microgravity has on both cancer and healthy cells functionality. In particular, we observed deactivation of Yap-1 molecule in glioblastoma cells and the remodeling of VE-Cadherin junctional protein in endothelial cells. The study provides support for the application of the proposed biological platform for advancing space mechanobiology research, also highlighting perspectives and strategies for developing next generation of brain cancer molecular therapies, including targeted drug delivery strategies.

Experimental Study on the Pressure Transfer Mechanism of Embedded Magnetic Fluid Seals

Although the sealing mechanism of the embedded magnetic fluid seal is unclear, it is an effective way to improve the performance of the ordinary magnetic fluid seal. Embedded magnetic seals can be divided into diverging and converging embedded magnetic fluid seals, according to the direction of leakage of the sealed medium. This article mainly focuses on presenting a sealing device that can observe the change in the shape of the magnetic fluid film and investigate the mechanism of diverging and converging embedded magnetic fluid seals. The pressure transfer mechanism of the embedded magnetic fluid seal with a large gap was studied through experiments. Numerical analysis of the magnetic field distribution in the seal gap and calculation of the theoretical pressure capacity of the embedded magnetic fluid seal are produced on the basis of embedded magnetic fluid seal theory. The experimental pressure capacity is compared with the theoretical pressure capacity to verify the correctness of the embedded magnetic fluid seal pressure capacity theory. The research has investigated the effect of the number of magnetic fluid film ruptures on the self-restoring capacity of embedded magnetic fluid seals, compared with the self-restoring capacity of diverging and converging embedded magnetic fluid seals, and analyzed the data. The results illustrated that the experimental pressure capacity of the embedded magnetic fluid seal matched well with the theoretical pressure capacity, which verifies the correctness of the embedded magnetic fluid seal theory. The pressure transfers from one chamber to another when the pressure difference between the two sides of the magnetic fluid film under the pole tooth is larger than the pressure capacity of the magnetic fluid seal, and the air will enter from the high-pressure side seal chamber to the low-pressure side seal chamber, in turn. As the inlet pressure increases, the pressure trend in the radial chamber of the embedded magnetic fluid seal differs from that in the axial chamber. When the seal fails, the magnetic fluid shows microleakage and complete leakage. As the number of magnetic fluid film ruptures increases, the self-restoring capacity first decreases and then increases. The self-restoring capacity of the converging embedded magnetic fluid seals is better than that of the diverging embedded magnetic fluid seals.

Occlusive Properties of Transrenal Ureteral Occlusion Self-Expandable Metallic Stents: 3D-Printed Phantom and Ex Vivo Studies

Newly developed transrenal ureteral occlusion self-expanding metallic stents (SEMSs) are applied in patients with inoperable fistulas. In this study, the occlusive properties of M- and D-type occlusion SEMSs were investigated in 3D-printed phantom and ex vivo porcine urinary tracts. In the former, the mean bursting pressure causing leakage of contrast medium through the occlusion SEMS was relatively higher in M-types (42.8 ± 3.8 mmHg) than in D-types (38.8 ± 3.8 mmHg), without a statistical difference (p = 0.075). In the latter, the bursting pressure causing leakage through the M-type occlusion SEMS (110.7 ± 8.6 mmHg) was significantly higher than that of the D-type occlusion SEMS (93.8 ± 11.2 mmHg, p = 0.015); however, the mean bursting pressures causing contrast blowout did not differ between the two types (178.7 ± 11.2 mmHg vs. 176.2 ± 11.8 mmHg, p = 0.715). In conclusion, M- and D-type occlusion SEMSs showed similar efficacy in occlusive properties in the 3D phantom study; however, the M-type was superior in the ex vivo porcine urinary tract model. Further in vivo experimental studies are required to confirm these experimental results.

Relationship between Transient Cortical Blindness and Contrast Medium Leakage That Occurs after Endovascular Treatment of Posterior Circulation Aneurysms.

The mechanism of transient cortical blindness after endovascular treatment-a rare phenomenon-has not been elucidated; however, it is assumed to be related to contrast medium leakage (CML). We investigated the relationship between postoperative CML and cortical blindness in patients who underwent endovascular treatment for vascular lesions of posterior circulation. This retrospective cohort study included 28 patients who underwent endovascular treatment for posterior circulation aneurysms at our hospital between January 2014 and December 2018. Cerebral CT was performed immediately after endovascular treatment and 24 h later. CT images were retrospectively evaluated with special interest in the presence and distribution of leakage of the contrast medium (CM). Patients were classified into the following three groups based on CT findings: Group A, no CML (11 patients); Group B, unilateral CML (5 patients); and Group C, bilateral CML (9 patients). The posterior circulation aneurysms were located in the basilar artery in 13 (52.0%) cases, in the posterior cerebral artery in 1 (4.0%) case, and in the vertebral artery in 11 (44.0%) cases. There was no difference regarding the adjunctive technique used for endovascular treatment between the groups. Patients in Group C used a significantly larger amount of CM than those in the other two groups. A longer operation time was associated with a larger amount of CM used during treatment. VerifyNow assay revealed that the P2Y12 reaction unit was significantly lower in Groups B and C. Cortical blindness was transiently observed in 2 of 9 patients (22.2%) in Group C, both of which showed CML surrounding the bilateral parieto-occipital sulcus. Both patients with cortical blindness showed bilateral CML, both of which showed CML surrounding the bilateral parieto-occipital sulcus. The CM-induced blood-brain barrier disruption may be the cause of cortical blindness.

Particulate matters filtration by a filter medium with pin holes: modeling and experimental verification

Air filtration systems have difficulty avoiding problems of leakage and breakage of the filter medium, which aggravates the emission of dust particles. In this study, a numerical calculation model is established to study the dust-laden air filtration performance of a filter medium with pin holes. The calculation model is verified using experiments and by comparing the values of the filtration resistance and efficiency. The results demonstrated that, with the existence of leakage, the filtration efficiency decreased with time, decreased with an increase in the leakage ratio, and increased first and then decreased with an improvement in the filter medium accuracy. An extremely high filter medium accuracy was not conducive to improve the filtration efficiency, but it obviously increased the filtration resistance. The larger the leakage ratio, Lr, the smaller the optimal filter accuracy, eF,opt, and the maximum filtration efficiency, eT,max. The functional relationships between eF,opt, eT,max and Lr, as well as QT, were obtained. With an increase in the leakage ratio, the filtration resistance and its rising rate decreased. The system quality factor decreased with the increase of the leakage ratio and increased with the increase of the filter quality factor.

Scroll compressor. Analysis of calculation methods

The paper deals with some aspects of mathematical modeling of a scroll compressor. Various approaches to modeling the working processes of machines of the volumetric compression principle, their applied value and priority of use are presented. An analytical review of the methods for calculating the leakage of a compressed medium, applied to a scroll compressor, taking into account the classification of slots, is carried out. Conclusions are made about the need to clarify the assumptions and improve this technique by taking into account the fact of the mobility of the walls of the gap, depending on the share of the influence of various factors on the leakage of the compressed medium. And also about the influence of this fact on the accuracy of calculations and the optimal choice of the operating mode of the compressor. Examples are given in which taking this condition into account in the transformed systems of equations will improve the accuracy in applied calculations of the working processes of spiral machines, when designing new samples.

Mortality rate of birds following intravenous administration of iodinated contrast medium for computed tomography.

To identify potential risk factors for death following IV or intraosseous (IO) administration of contrast medium in birds undergoing CT scans. 120 birds that underwent 134 contrast-enhanced CT scans. Medical records of birds of any species that underwent a CT scan which included administration of nonionic iodinated contrast medium from June 2013 to February 2020 were included. Information on birds and use of contrast medium was extracted from the medical records as well as information on deaths following IV or IO administration of contrast medium. 6 birds died shortly following administration of contrast medium. Necropsies were performed in 3 birds (2 cockatiels and 1 macaw), and all had lesions associated with the respiratory tract. When body weight was used as a binary variable to compare odds of death between small birds (≤ 150 g [0.33 lb]) and large birds (> 150 g), small birds had a 97-fold increased odds (OR, 97.5; 95% CI, 9.8 to 966.0) of dying following contrast medium administration. Following 131 CT scans with contrast medium administration (3 scans were excluded because of perivascular or subcutaneous leakage of contract medium), small birds had a mortality rate of 45.4% (5/11), compared with a mortality rate of 0.8% (1/120) for large (> 150 g) birds. Other variables (ie, sex, age, anesthesia or sedation, sedation protocol, and type of contrast medium) were not significantly associated with death after contrast medium administration. Although the administration of contrast medium cannot be conclusively confirmed as the cause of death in these birds, the high mortality rate for small birds coupled with the temporality of the event following contrast medium administration justifies the cautious use of contrast medium in small sick psittacine birds.

Embolization for massive bleeding due to spontaneous left external iliac vein rupture: report of a successful case

BackgroundSpontaneous rupture of the iliac vein has rarely been reported. Its associated hypovolemic shock-related symptoms and signs, including syncope and hypotension, have been observed in most of these cases. Successful transcatheter venous embolization for massive bleeding due to spontaneous rupture of the external iliac vein was herein reported.Case presentationAn 82-year-old female patient developed sudden left lower abdominal and back pain. Immediately, she lost consciousness and went into shock. CT images of her abdomen revealed a huge retroperitoneal hematoma, with leakage of contrast medium in the hematoma in the left flank. These findings suggested left external iliac vein rupture.Open surgery was considered; however, since the patient’s condition may have deteriorated further due to the time needed to prepare for surgery, including general anesthesia, transcatheter venous embolization of the left iliac vein was selected. A 5.2-Fr compliant balloon catheter (nominal diameter of 10 mm) was inflated at the distal site of the external iliac vein to reduce extravasation. N-butyl-2-cyanoacrylate (NBCA) was mixed with Lipiodol at a ratio of 1:2. The left Iliac vein was filled and completely embolized with the NBCA/Lipiodol mixture (total injected volume, 5 mL) using a 1.8-Fr microcatheter. After embolization, the patient quickly. An inferior vena cava filter was placed 1 day after embolization.ConclusionSpontaneous rupture of the iliac vein is a very rare and lethal condition. Transcatheter venous embolization may control potentially life-threatening bleeding. Rapid bleeding control in a critical condition is facilitated by this minimally invasive approach.